Some square like symbols similar to : http://tex.stackexchange.com/questions/48471/how-to-generate-the-movie-dvd-available-sound-systems-symbols
appear on the back of DVDs, with various number of little solid squares, any hints on what they are called? googling "movie, symbol, subtitlle, dolby" etc. brings up completly irrelevant results.
I am not even sure what to tag this question as.